Reaction: S-adenosyl-L-methionine + demethylphylloquinol = S-adenosyl-L-homocysteine + phylloquinol
For diagram of reaction click here.
Glossary: demethylphylloquinol = 2-phytyl-1,4-naphthoquinol
phylloquinol = 2-methyl-3-phytyl-1,4-naphthoquinol = vitamin K1
Other name(s): menG (gene name); 2-phytyl-1,4-naphthoquinol methyltransferase
Systematic name: S-adenosyl-L-methionine:2-phytyl-1,4-naphthoquinol C-methyltransferase
Comments: The enzyme, found in plants and cyanobacteria, catalyses the final step in the biosynthesis of phylloquinone (vitamin K1), an electron carrier associated with photosystem I. The enzyme is specific for the quinol form of the substrate, and does not act on the quinone form .
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
1. Sakuragi, Y., Zybailov, B., Shen, G., Jones, A.D., Chitnis, P.R., van der Est, A., Bittl, R., Zech, S., Stehlik, D., Golbeck, J.H. and Bryant, D.A. Insertional inactivation of the menG gene, encoding 2-phytyl-1,4-naphthoquinone methyltransferase of Synechocystis sp. PCC 6803, results in the incorporation of 2-phytyl-1,4-naphthoquinone into the A1 site and alteration of the equilibrium constant between A1 and F(X) in photosystem I. Biochemistry 41 (2002) 394-405. [PMID: 11772039]
2. Lohmann, A., Schottler, M.A., Brehelin, C., Kessler, F., Bock, R., Cahoon, E.B. and Dormann, P. Deficiency in phylloquinone (vitamin K1) methylation affects prenyl quinone distribution, photosystem I abundance, and anthocyanin accumulation in the Arabidopsis AtmenG mutant. J. Biol. Chem. 281 (2006) 40461-40472. [PMID: 17082184]
3. Fatihi, A., Latimer, S., Schmollinger, S., Block, A., Dussault, P.H., Vermaas, W.F., Merchant, S.S. and Basset, G.J. A dedicated type II NADPH dehydrogenase performs the penultimate step in the biosynthesis of vitamin K1 in Synechocystis and Arabidopsis. Plant Cell 27 (2015) 1730-1741. [PMID: 26023160]